Download - Tissues and Membranes
Tissues and Membranes
Anatomy chapter 5
Body Tissues
• A tissue is a group of cells that have similar structures and that function together as a unit.
• Histology – the microscopic study of tissues.
• There are 4 main tissue types in the body:
Epithelial Muscle
Connective Nervous
Tissue types
EPITHELIAL TISSUE
Epithelial Tissue• Widespread throughout the body
• Cover body surfaces• Line body cavities• Major tissue in glands• It always has a free surface – exposed to the
outside or to open space internally• Jobs include protection, secretion, absorption,
filtration, diffusion, and sensory reception
Epithelial Tissue types
Epithelial tissue
• Tightly packed cells – very little intercellular matrix (the substance between cells)
• Cells are attached to underlying tissue by the basement membrane, which is nonliving. • The basement membrane is a mixture of
carbohydrates and proteins.
Basement membrane
The epithelial cells above receive their nutrients by diffusion from the blood vessels in the underlying tissues.
Epithelial tissue
• Are avascular – which means they have no blood supply directly.
• Reproduce quickly (divide readily)
• Are classified according to cell shape and number of layers in the tissue.
Epithelial types
Squamous cells are flat; the nuclei are broad and thin.
Cuboidal – cubelike, the nuclei are spherical and centrally located.
Columnar – are tall and narrow, nuclei are usually near the base
Simple squamous epithelium
• A single layer of thin, flat cells that fit closely together.
• Alveoli in lungs• Capillary walls• Tissue is damaged
easily.
Simple squamous
Simple Cuboidal Epithelium
• A single layer of cube shaped cells.
• Linings of many glands• Lining of kidney
tubules• Absorption and
secretion
Simple Cuboidal
Simple Columnar Epithelium• Single layer of cells
that are taller than they are wide.
• Lining the stomach and intestines, also lines the uterus
• Secretes digestive enzymes, absorbs nutrients
Simple columnar
Simple columnar
• Where absorption is necessary, these cells may have microvilli.
• Goblet cells secrete mucus.
• Cilia may be present
Pseudostratified Columnar Epithelium
• Appears to have multiple layers, but it really does not.
• All cells attached to basement membrane.
• Commonly have cilia• Usually in respiratory
and male reproductive tract.
Pseudostratifed Columnar
Stratified Squamous Epithelium
• The most common type of layered epithelium.
• Many layers of cells.• Cuboidal at the
basement membrane, become thinner near the surface.
Stratified Squamous
Stratified Squamous• Cells at the basement membrane undergo
mitosis.
• The cells die as they are pushed further from the basement membrane.
• Outer layer of skin
• As skin cells age, they accumulate keratin (a protein) and then harden and die.
Stratified Cuboidal Epithelium
• Two or three layers of cuboidal cells that form a lining of the lumen.
• More protection than 1 layer.
• Lines sweat, salivary and mammary glands, also the pancreas
Stratified Columnar Epithelium
• Several layers of cells.• Superficial layer are
columnar, basal layers are cuboidal.
• Found in the pharynx, also in the male urethra.
Transitional Epithelium
• A specialized type of tissue with several layers, but can be stretched in response to tension.
• The lining of the bladder is an example.
Transitional epithelium
Glandular epithelium
• Consists of cells that are specialized to produce and secrete substances.
• Lies deep (underneath) epithelium that cover and line parts of the body.
• Exocrine glands secrete their products onto a free surface via a duct.
Types of glandular epithelium
• Simple tubular – the ducts have no branches.
• The gland and duct merge with no change in diameter.
Types of glandular epithelium
• Compound acinar• Has branches
(compound)• Has sacs (acinar)• This type is also called
alveolar
Gland classified by mode of secretion
• Merocrine glands – use exocytosis, no cytoplasm is lost. Example: salivary glands
• Apocrine glands – Product accumulates in an area of the gland, then is pinched off – a small portion of the cell is lost. Example: sweat glands
• Holocrine – the entire cell ruptures, releasing products. Example: Oil (sebaceous) glands
CONNECTIVE TISSUE
Connective tissue
• Binds structures together
• Form a framework and support for organs and the body.
• Store fat
• Transport substances
• Protect against disease and repair tissue damage.
Connective tissue• Cells can reproduce, but not as quickly as
epithelial tissue.
• Three types of fibers embedded in intercellular matrix – collagenous fibers, elastic fibers and reticular fibers.
• Many cell types in connective tissue. Most common are mast cells, macrophages, and fibroblasts
Connective tissue cells
• Fibroblasts – Most common. Large cells secrete proteins into the extracellular matrix.
• Macrophages – Originate as white blood cells and carry on phagocytosis. Can move about
• Mast Cells – Large cells usually near blood vessels. They release heparin and histamine.
Fibers• Collagenous fibers – thick threads of the protein
collagen. Grouped in bundles. Flexible but only slightly elastic. Important parts of ligaments and tendons.
• Elastic – composed of the protein elastin. Weaker than collagenous, but stretch easily. Vocal cords.
• Reticular – Very thin collagenous fibers. Highly branched and form a supporting network in organs like the spleen
Types of connective tissue• Loose connective tissue
• Adipose tissue
• Elastic connective tissue
• Dense fibrous connective tissue
• Cartilage
• Bone
• Blood
Loose connective tissue
Loose connective tissue
• Also called areolar CT• Packing material in the
body• Attaches skin to
underlying tissue, fills spaces between muscles.
Adipose tissue
• Better known as fat• Cells can take up fat
and release it at a later date.
• Acts as a cushion for the body, insulator for heat.
Reticular connective tissue
Dense Fibrous Connective Tissue
• Closely packed parallel bundles of collagenous fibers.
• Make up tendons and ligaments
Elastic Connective Tissue
• Closely packed elastic fibers.
• Yields easily to pulling force.
• Vocal cords and vertebral ligaments
Cartilage
• Has an abundant matrix – solid, yet flexible
• Cartilage cells are called chondrocytes
• Heals slowly – no direct blood supply
• Protects underlying tissues, supports structures, and is a framework
3 types: hyaline, fibrocartilage, and elastic
Hyaline cartilage
Hyaline: most common type
Found at the end of long bones
Most of the fetal skeleton is made of this before it is replaced by bone
Fibrocartilage
• Abundance of strong collagenous fibers.
• Acts as shock absorber• Found in between
vertebrae and between the bones in the knee joint.
Elastic Cartilage
• Much more flexible than hyaline or fibrocartilage.
• Found in outer ear.
Bone
• Most rigid connective tissue
• Arranged in concentric rings
• Form a framework for body, and attach muscles
Bone tissue
Blood
• Unique because it has a liquid matrix.
• Erythrocytes – red blood cells
• Leukocytes – white blood cells
• Plasma – liquid matrix
• Platelets – fragment of a cell in the bone marrow.
Blood
Blood components
• Red blood cells
• White blood cells
• Platelets
• Plasma – plasma is 95% water• Other 5% is salts, nutrients, hormones, and
proteins.
Web sites
• Goto http://msjensen.cehd.umn.edu/default.asp
• Click on image bank and review some images of types of tissue
• Click on self-test and choose a test to take. Use your notes and identify tissue types and structures.
MUSCLE TISSUE
Muscle Tissue
• Made up of cells that have an ability to shorten or contract to produce movement.
• Highly cellular – good blood supply
• Arranged usually in bundles or layers.
• 3 types: skeletal, cardiac, and smooth
Types of muscle tissue
Skeletal muscle
• What we usually think of as “muscle”
• 40% of body weight• Fibers are long and
cylindrical with many nuclei
• Cell has a striated appearance.
Skeletal muscle
• Muscle fibers are collected into bundles and wrapped in connective tissue.
• Skeletal muscle is voluntary
Smooth muscle
• Found in the walls of hollow body organs – stomach, intestines, etc.
• Lacks striations• Also called involuntary
muscle
Cardiac muscle
• Found only in the heart wall.
• Look similar to striated muscle
• One nucleus per cell• Involuntary contraction
NERVOUS TISSUE
Nervous tissue
• Found in brain, spinal cord and nerves
• Responsible for coordinating and controlling body activities.
• Communicates by way of electrical nerve impulses.
• Nerve cells - neurons
Neurons
INFLAMMATION AND TISSUE REPAIR
Inflammation
• A defense mechanism that attempts to contain tissue injury and prepare for healing.
• Symptoms: redness, swelling, heat, pain.
• It is a beneficial process, even though it may be painful.
Inflammatory process
• Blood vessels dilate, become more permeable
• Increased blood flow to area
• Fluid and WBC’s leave vessels and go into tissue space. WBCs engulf debris and bacteria.
• Fluid dilutes toxins and contains clotting proteins.
Tissue Repair
Regeneration
• Replacement of destroyed tissue by proliferation of identical cells.
• Occurs only in tissues that can undergo mitosis
• Skeletal muscle, cardiac muscle, and nerve tissue cannot regenerate.
Fibrosis
• Replacement of destroyed tissue by fibrous (scar) tissue
• Collagen fibers form the basis of the scar.
• Immature scar tissue is called granulation tissue.
• Scar may be visible or not depending on the severity of the wound.
BODY MEMBRANES
Body Membranes
• Thin sheets of tissue that cover the body, line body cavities, cover organs, and line the cavities in hollow organs.
• Skin is a membrane
• Membranes may be epithelial or connective tissue.
Epithelial membranes
Mucous membranes
• Epithelial tissue that is attached to loose connective tissue.
• Line the body cavities that open to the outside
• Examples: digestive tract, respiratory, excretory, and reproductive tracts.
Serous membranes
• Line body cavities that do not open directly to the outside.
• Thin layer of loose connective tissue covered by a layer of simple squamous epithelium.
• Covered by a thin layer of serous fluid.
Mucous membranes
Serous membranes
Connective tissue membranes
Synovial membranes
• Line the cavities of the freely moveable joints, like the shoulder, elbow and knee.
• They secrete synovial fluid into the joint cavity, which lubricates the cartilage.
Meninges
• Connective tissue coverings around the brain and spinal cord.
• Provide protection.
• Meningitis is inflammation of the meninges.
Synovial membranes
Meninges
Meninges
Cell communication
• Interactions between cells are vital to the function of other cells, tissues, and organs.
• All cells are signaled to survive and carry out homeostasis (maintenance of a constant internal state).
• All cells need energy to carry out functions.
Methods of cell communication
• Most common way that cells communicate is by chemical means.• Hormones • Signal receptors (like a lock and key)• Proteins
Specific examples of hormone communication
• Cell division
• Immune response
• Production of enzymes or proteins
• Blood clotting
Other methods of cell communication
• Cell to cell contact
• Electrical impulses (SA node in the heart, axons in the nervous system)